Off Center Fed (OCF) Dipole Baluns

439679433 - Off Center Fed (OCF) Dipole Baluns
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Shortwave Listener Antenna - with MLB-2 Magnetic Longwire unun, 50 foot antenna wire, 25' support cord, end insulator

PA-SWL-1
$109.95
In stock
1
Product Details
Brand: Palomar Engineers

Model # PA-SWL-1 includes MLB-2 Long Wire antenna matcher, 50 feet of insulated wire and 25 feet of support cord and a end insulator for the antenna. Great for short wave listening and works as a bent antenna, sloper, inverted “L” antenna (Vertical and horizontal) or as a straight vertical antenna. For best results use a counterpoise for the lower frequencies.

Palomar Engineers Magnetic Longwire Balun has been redesigned for shortwave listeners and others needing to match a long wire antenna to 50/75 ohm coax feed line cable.

Specifications: Frequency: 100 KHz – 30 MHz. Input: 50/75 ohms for coaxial cable. Output: High impedance. Connector: SO-239 (for cable) wingnut/solder lug for wire lead (for antenna). Mounting: Stainless steel eyebolt. Size: 2.5” diameter. Case: White PVC sealed weatherproof. External ground bolt with wing nut for external counterpoise or separate ground.

The long wire antenna often has a high impedance in the 500-1000 ohm range and the MLB-2 transforms this high impedance close to 50/75 ohms efficiently coupling the received signal to the receiver. A long wire antenna with a matching unit such as the MLB-2 often has a 12 db (2 “S” units) better signal than a long wire without a matching unit.

For best results use a coax noise filter at the receiver end of the coax to reduce common mode noise picked up by the coax braid. Model # CMNF-500-50 is best suited for this antenna.


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Testimonial

Hi Bob,

Radio: Flex-6700 running barefoot -10 to 100 Watts max.
Antenna: MFJ-1216 – 160/80 meter OCFD wire antenna with matching network.
Elevation: Over 60 feet AGL – fully extended.
Installed: Mid November 2013

I operate mainly on the digital modes running less than 50 Watts.  All of the sudden after a few days operating with this antenna, I start to have RFI and my radio was acting up; such as changing bands, SWR changing values, radio failures and turning off. However, when I used my Hy-Gain 18 HT vertical on the same band none of the abnormality occurred.
I contacted MFJ and confirm that what I was noticing was a failure of their “matching network” AKA balun.  They offered no solutions. Then I contacted Palomar Engineers and bought the 1:1 new toroid RF beads.  I called Palomar Engineers and I happened to talked to you directly; regarding the on going issue with the MFJ antenna. I found out that the 1:1 balun was not what I needed (I was miss-informed by MFJ that it was 1:1 matching network.)
You offered to make the required balun 4:1 and the rest is history.

Here are my findings:

  1. No more RFI displayed on the monitors.
  2. Radio not acting up or turning off.
  3. The SWR at 160/80 meter is 1.2:1
  4. No antenna tuner required.  (radio goes to Bypass automatically.)
  5. Worst SWR is on 10 meter with a 2:1 but still usable, with antenna tuner 1.5.
  6. One happy OCFD user!

Thanks to Palomar Engineers design and engineering for solving this issue.

73, Ernest – W4EG